1. Field of the Invention
This invention relates to electro-mechanical connectors for circuit boards, and more particularly to edge connectors that mechanically secure and electrically connect the edge portions of circuit boards.
2. Description of the Related Art
A typical computer is highly modular. During a computer""s useful life, usually one or more components are replaced, either due to system maintenance or upgrades. Most computer components are designed to be replaceable and are supported on a xe2x80x9cpluggablexe2x80x9d printed circuit board. With technological progress, computers are continually operating at higher frequencies and increasing circuit density. The number of components normally installed as part of a computer system has therefore increased, yet consumers expect computers to increasingly become smaller and lighter. With limited space in a computer chassis to contain these components, circuit boards have become more closely packed.
Electrical connectors are designed to provide conductive paths between adjacent circuit boards. With increasing circuit density, the electrical connectors and the electrical terminals they include are smaller and there are more of them.
Connectors between adjacent circuit boards are often installed on a primary, or xe2x80x9cmotherxe2x80x9d board, and are adapted to receive the edges of secondary, or xe2x80x9cdaughterxe2x80x9d boards. These connectors connect the edge of the daughter board to a socket on the mother board. Often daughter boards are installed such that the daughter board is perpendicular to the motherboard. These connectors are called edge connectors and are used in modem electrical equipment that contains a number of parallel daughter boards that are closely packed together.
Edge connectors often comprise a number of conductive contacts that are spaced apart and arranged linearly in a housing. Each contact is metallic, and is positioned to abut a conductive contact on the edge of the daughter board. Often the contacts are arranged in two parallel rows so the daughter board can be inserted between the rows. When a daughter board is positioned between the rows, the contacts exert a gripping force on the daughter board so as to secure it in the housing.
One disadvantage to using edge connectors in this way is that the increasingly smaller sizes of motherboards limit the number of sockets and therefore the number of components that can be installed. Furthermore, with increased density of components and connections within the computer chassis, assembling a computer or replacing a component is an intricate process. Moving a circuit board during assembly complicates the process and compromises electromagnetic shielding. Minimizing the number of components to be moved and designing the system to move less complex components simplifies assembly and replacement of components. A simplified mechanical design also minimizes the amount of electromagnetic interference between these closely packed components. Finally, optimizing the layout of components in the limited space within the chassis is necessary to meet consumer demands for smaller and lighter computers.
What is needed is an inexpensive device, which allows for dense placement of circuit boards within a computer chassis, while minimizing the number of complex components to be moved, limiting electromagnetic interference, and optimizing the layout of components within the chassis.
In one embodiment of the invention, a card edge connector has at least two card-receiving areas for receiving at least two circuit board edges. The card edge connector includes an electrical contact for electrically connecting with an electrical contact on the edges of each of the circuit boards.
In another embodiment of the invention, each card edge connector electrical contact is formed from a continuous piece of metal. Each connector electrical contact thereby can contact electrical contacts on more than one circuit board simultaneously, thereby forming an electrical connection between multiple circuit boards.
In another embodiment of the invention, an apparatus includes at least two circuit boards and a card edge connector with card-receiving areas for receiving the edges of the circuit boards and forming an electrical connection between the circuit boards. The card edge connector is designed to be removably installed on one circuit board and to connect with an electrical contact on the edge of another circuit board.
The connector electrical contacts touch the electrical contacts of the edge of the circuit board when the edge is inserted into the respective card-receiving area of the connector. When the connector is placed between the circuit boards and the respective card edges are inserted into the respective card-receiving areas, the connector establishes an electrical connection between the circuit boards.
In another embodiment, each circuit board is installed within the apparatus in a fixed position. The card edge connector is adapted to slide, or translate, over the circuit board edge on which it is installed and onto the electrical contacts of the edge of at least one of other circuit boards. The electrical connection is established between the fixed circuit boards, which remain stationary while the card edge connector slides to form an electrical connection between them.
In another embodiment of the invention, a computer system includes a processor, a motherboard for the processor, a memory, and the card edge connector described above.
A further embodiment is a computer system as described above, where the motherboard is split into two circuit boards, a motherboard proper and a smaller detachable expansion board. The edge connector is installed on either the expansion board or the motherboard proper and slides to connect with electrical contacts on the other. This embodiment allows the expansion board to be placed within the computer system to maximize space for adding components, and yet provides the necessary connection of the components to the motherboard proper. The motherboard proper and the expansion board are stationary while the electrical connection is made between them.